Information Centric Network (ICN) is technology proposed to overcome a traffic congestion phenomenon which is a disadvantage of the conventional IP address-based communication scheme. The Internet usage is now increasing rapidly in terms of the number of users and data capacity. According to the existing IP address-based data transmission scheme, transmission is performed using the IP address of the receiver related to the physical location, which is inefficient because the same data is repeatedly transmitted on the network as many times as the number of service requests.
ICN is a communication approach based on the data name rather than an IP address, in which routers or nodes store specific data and distribute data to neighbor routers or nodes that request the corresponding data. In ICN, a message may be classified into interest information and data. A consumer or a data requester that needs data may disseminate interest information via the network. When receiving the interest information, a router, node or data provider possessing the requested data through the interest information may deliver the data to the consumer or the data requester through a reverse path used to deliver the interest information.
Specifically, in ICN, interest information and data may be delivered using Content Store (CS), Pending Interest Information Table (PIT) and Forwarding Information Base (FIB). CS may be a storage device such as buffers of routers and nodes, and may be used to store data and data name lists. PIT may be used to store input/output records of interest information. The input/output records may include incoming and outgoing faces. When routers and nodes receive interest information, the routers may transmit the interest information to a probable node and store input/output records of the interest information in PIT. When receiving data corresponding to interest information, routers and nodes may check PIT, transmit the data via the incoming face to which the interest information is inputted, and delete the corresponding interest information. FIB may be responsible for delivery of interest information and delivery control.
Looking at the communication scheme in ICN, when interest information is received at routers and nodes, a determination may be made as to whether the data name stored in CS of the routers and the nodes matches the name of the interest information. When the name stored in CS of the routers and the nodes matches the name of the interest information, the corresponding data is present in CS, and thus the routers and the nodes may check PIT and transmit the corresponding data via a reverse path through which the interest information is delivered, and delete the interest information.
Additionally, when the name of the received interest information is present in PIT, the incoming face of the corresponding interest information may be added to PIT. That is, it is regarded that a new consumer or data requester of the corresponding interest information is added. Here, the new consumer or data requester may be identified by a random variable stored in the interest information.
Additionally, when the name of the received interest information is present in FIB, the name of the corresponding interest information and the incoming face may be added to PIT, the corresponding interest information may be transmitted to other routers or nodes, and the outgoing face may be stored. On the contrary, when the name of the received interest information is absent in FIB, a service for the corresponding data is impossible, and thus the corresponding interest information may be deleted.
Meanwhile, when data is received at routers and nodes, a determination may be made as to whether the received data is stored in CS by identifying the data name stored in CS of the routers and the nodes. When the name of the received data is present in CS of the routers and the nodes, the received data may be deleted.
Additionally, when the name of the received data is present in PIT, the received data is the requested data, and thus the received data may be stored in CS, and the corresponding data may be transmitted to the incoming face of the interest information. On the contrary, when the name of the received data is absent in PIT, the received data is not the requested data, and thus the received data may be deleted.
In ICN, each node may transmit an interest information message to request data. Thus, a source node having received the interest information may deliver the data using a reverse path through which the interest information is delivered. Accordingly, ICN can be only applied in a network environment in which the connectivity between nodes is guaranteed, and it is difficult for ICN itself to be applied to a delay tolerant network environment in which connectivity between nodes is not guaranteed.